Electron apparatus



July 14, 1942 c; s. YEUTTER I ELECTRON APPARATUS Filed July 9, 1941 FIG-3 INVENTOR C. S. VEUTTER BVJ ATTORNEY Patented i I Clyde S. Yeutter,

Telephone Laboratorl York, N. Y., acorporat ELECTRON APPARATUS Oradell, N. 1., ass lnor to es, 4. Incorporated, ion 01' New York Application July 9,1941, Serial No. 401,560

4 Claims. (01. 171-95) This invention relates to a-hot cathode electron apparatus and, more particularly, to an arrangement to compensate for variations in magnitude of the heater energizing voltage in such apparatus. Q

Heretofore, in the operation of a hot cathode .electron'apparatusin a measuring circuit, it has been found that variations in the magnitude of the voltage energizing the heater caused different changes in the resistance of both the anodecathode and heater circuits. Such resistance changes effect undesirable variations in the current of the anode-cathode circuit, and, accordingly, introduce errors; in the meter readings occasioned by this current.

The main object of the invention isto'obtain accurate readings in a measuring device embodying'hot cathode'electron apparatus.

Another object'is to compensate for variations of the voltage energizing the heater of hot cathode electron apparatus.

The same reference numerals are employed to identify the same elements appearing in the several figures of the drawing.

Referring to Fig. 1, a thermionic electron device Ill comprises a heater II, a cathode 12, con trol grid .l3, anode l4, screenelectrode and suppressor grid l3.

The heater l I is energized in a circuit embodying in series positive terminal of source 2|,. of directpotentialflead 22, common terminal 23,

, lead 24, heater l I, lead 23, iixed resistorsnand A furtherobject is to control the effective anode-cathode curi'ent of hotcathode electron apparatus. I

In a specific embodiment, the present invention comprises 'an electron/device embodying a hot cathode, a heater, a control grid,'and an anode, and connected such that the anode-cathode cir-' cuit includes a-source of direct potential to energize the anode, and the heater circuit provides a source of direct potential to energize the heater. A resistance. bridge network embodying an indicator across one diagonal and connecting effectively the other diagonal in the anode-cathode -,and heater circuits serves to produce an initial zero reading on the indicator at no voltage input to the control grid-cathodepcircuit. The ratio arms connected in the respective anode-cathode and. heater circuits. are provided with such.

amounts of resistance that the resistance ratio therebetween is maintained substantially constant regardlessof variations in the magnitude of theheater-energizing voltage." This tends to control the amount of current flowing in the anode-cathode circuit to compensate for variations in the-magnitude of the heater energizing; v vol tage. This .hot' cathode electron device is '21 in series, common terminal ing in series from 28, lead 23 and the negative terminal 01' the source 2|. r The anode I4 is energized in a circuit extendthe positive terminal of source 33 of direct potential, lead 34, anode I4 and cathode I2, lead 35, fixed resistor 33 and adjustable resistor 31 in series lead 33, common-terminal.

28,- lead 29, sourcell, lead 22, common terminal 23, and back to the negative terminal of the source 33.

A progressively increasing negative voltage E to be measured is applied across the input terminals 39 and", of which the terminal 39 is connected by lead 4| to the control grid l3, and the terminal 40 is connected by lead 42 to a link 43 extending from the common terminal 23 and terminating in ground 44. A resistor 46 is connected across the input terminals 33 and 4D. Across the mid-points oi the series resistors 28 and 21 and 33 and 31 is disposed an indicator 45.

arranged to measure progressively increasing amounts of negative voltage.

, The inventionwill be readily understood from thefollowing detailed descriptlonl'taken together with the accompanying drawing, in which:

,Fig. 1 is aschematic circuit illustrating a speciflc embodimentiqi theinvention; and 1 Figs. 2 and; 3, showmodlflcations" oi. Fig. 1.

sponding opposite ends of resistors sister :1 is actuated until the an initial zero reading. 7 This means that when Thecontrol grid I3 is supplied with a suitable negative biasing voltage eii'ective over a circuit extending irom the negative tenninal or the source 33, common terminal 23, link 43, lead 42, resistor 43, lead 4| to the control grid l3.

The resistors 26, 21, 36 and 31 constitute a bridge network 46 in which a horizontal diagonal comprising the common terminal 28 and cone- 23 and 33-is efiectively connected in both the previously described heaterand anode energizing circuits, and a vertical diagonal embodies the indicator 4!.

In the operation of Fig. 1, the adjustable reindicator 43 shows the heater II is energized with a constant magnitude of voltage from the source 2|, the anodecathode current flowing in the resistor 36 divides such that a portion flows in the indicator 45 and resistor 21 to. the common terminal 23 while another portion flows in the adjustable resistor 31 and lead 33, to 'thecommon terminal 23.,"

Hence, for this zero reading, the bridge 1' "embodying the resistors as and" havea certain 11 causes the,cathode ratio."

heater II, the resistance of the latter decreases with an increase'in the magnitude ofthe energizing voltage therefor near the operating point of the heater ll.

Assuming a decrease in themagnitude of the voltage of the heater energizing source 2|, the iollowing action takes place simultaneously: (1) the efiective negative biasing voltage on the control grid II is increased as the decreased positive voltage tends to increase the effect of the negative biasing voltage of the source 33 in the biasing circuit traced previously; (2) the heater ll causes the cathode I! to decrease the emission of electrons thereby increasing the resistance of the anode-cathode circuit; and (3) due to the non-linear current-voltage characteristic of the heater H, the resistance of the latter increases with a decrease in the magnitude of v the energizing voltage therefor near the operat-,

ing point of the heater H.

The increase or decrease in the magnitude of the heater energizing voltage of the source 2! changes the ratio of bridge arms embodying, the resistors 26 and 36 troduced in the re ding o! the indicator l5.

Hence, the measurement of the input voltageE will tend to be erroneous.

To overcome such tendency, the resistance of the previously described anode-cathode and source 2!, the

ch that'variations' are inheater energizing circuits is built out by increasing the amounts of the respective linear resistances 38 and 26 such that a substantially constant ratio exists between'the bridge arms embodying-the latter tworesistances for variations of the magnitude of the voltage of the source 2|. Consequently, variations of the magnitude of the voltage of the heater energizing source 2| will have substantially no eflect on the readings of the indicator 4!.

In the operation of Fig. 1, the c librated resistor 31 is initially actuated to produce a zero reading on the indicator when no voltage is applied across the terminals 39 and 0 as hereinbefore explained. So the negative voltage E of progressively increasing magnitude is impressed on the latter terminals, the eflective biasing volt- 1 age on the control grid 13 is correspondingly reduced to cause an increase in the fiow of current in the anode-cathode circuit. This increase is recorded on the indicator 4!. .In other words, the substantially constant ratio between the bridge arms 28 and 38 serves to render the indicator responsive only to variations in the voltage E impressed on the terminals 3! and 40.

Figs. 2 and 3 illustrate other modifications oi the bridge network 48. In this connection itis to be understood that the circuit portions in- Fig. 2 is substantiailyidentical with Fig. 1 in that the entire resistance or the anode cathode circuit is varied, while in Fig. 3 the entire resistance of thehea'ter circuit is varied.

In a specific embodiment of Fig. 2, the elements of the bridge network 46 comprised the following resistance values:

Resistance 26:1? ohms Resistance 21:15 ohms p Resistance 36=45,000 ohms Resistance 31:4,000 ohms Resistance 50=8,0(i0 ohms In a specific embodiment of Fig, 3, the elementsof the bridge network 46 comprised the following resistance values:

.Resistance 26:12.7 ohms Resistance 21:14 ohms Resistance 36:45,!)00 ohms Resistance 31=10,200 ohms Resistance 5I=5 ohms What is claimed is:

1. In combination, in an electron discharge system, an electron device including. a cathode. a cathode heater and an anode, circuit means to connect said anode and cathode, a source of direct potential in said anode-cathode circuit 'means,-other circuit means connected across said heater, a source of direct potential in said other circuit means, and means to maintain substantially constant the ratio of the resistance.

of said anode-cathode circuit means to the resistance of said other circuit means for variations in. the magnitude of the voltage of said heater source, comprising a bridge network' hava ing one diagonal eflectiveiycon'nected; in both said anode-cathode circuit means and said other circuit means, and an indicatorapplied across the other diagonal of geaid network.

2. In combination, in an electron discharge system,-an electron device comprising acathode,

a cathode heater and' an anode, circuit means to connect said anode and cathode, a source of direct potential in said first-mentioned circuit 'means toenergige said anode, furthercircuit means connected across said heater, a source of direct potential in said-further circuit means to energize said heater, and a resistance bridge network connecting both said anode-cathode. and heater circuit means such that a first pair of'arms is eiIectively in said anode-cathode'circuit means, a second pair oi. arms is effectively in said further circuit means, and a terminal eluded between the lines x-x and Y-Y in either of Figs. 2 and 3 may be substituted for the circuit portion included between the corresponding I lines x--x and Y-Y er mg. 1. n is noted that connecting corresponding ends oi both said first and second pairs of arms iscommon to both said anode-cathode and heater circuit means,

the resistance of corresponding individual arms of said first and second pairs of arms proportioned to maintain a substantially constant ratio for variations in the ,magnitude of the voltage of said heater energizing source, and mindicator applied across the mid-points of both said first and'second pairs of arms. 3. In combination, in an electron a cathode heater, and an anode, circuit means to connect said anode and cathode, a source of direct potential in said first-mentioned circuit means to energize said anode, further circuit means applied across said'heater, a source of direct potential in said further circuit means to energize said heater, a resistance bridge network connecting both said anode-cathode and heater circuit means such that a first pair of arms, one

discharge" system, an electron device comprising a cathode,

of which is adjustable, is connected efiectively in said first-mentioned circuit means in series with said anode-cathode energizing source, a second pair of arms is eii'ectively connected in said iurther circuit means in series with said heater energizing source, and a terminal is com mon to both said first and secdnd pairs of arms, corresponding individual arms of said first and second pairs of arms proportioned to maintain a substantially constant ratio for variations in the magnitude of the voltage of said heater energizing source, and an indicator applied across mid-points of said first and second pairs of i 4. In combination, in an electron discharge system, an electron device comprising a cathode, a cathode heater. and an anode, circuit means to connect said anode and cathode, a sourogeoi' direct potential in said anode-cathode circuit necting both said anode-cathode and heater circuit means such that a first pair of arms each embodying an individual resistor isconnected efiectively in said anode-cathode circuit means in series with said anode-cathode {energizing source, a second pair of arms each embodying an individual resistor is eflectively connected in said further circuit means in series with said heater energizing source, a resistor is interposed in series intermediate said second pair of arms, and a terminal is common to both said first and second pairs of arms,- corresponding individual resistors of both said first and second pairs of arms proportioned to maintain a substantially constant ratio for variations in the magnitude of the voltage of said source in said further a circuit means, and an indicator having one termeans, further circuit means applied across said 20 cathode heat r, 8. source of direct potential in said further circuit means, a bridge network conminal connected to the mid-point of said first pair of arms and another terminal connected adjustably to said last-mentioned resistors.

CLYDE S. YEUTTER. 

